If you are cinnected to the internet there are people who know how to get into your computer, passeord or no password They are called 'hackers'. For many its super easy. There are children who know how to do it. Esp if your pw isnt very strong. Could be anyone getting in your account from your brother to your neighbor to a total stranger. A big deal now is for hackers to 'kidnap' an account and demand money or something to unlick the computer - or they wipe it out with a virus. No account is totally secure.
my question is that even no one have my wifi password and no one have access to my internet... im the only user... so who else can block my mac address?
If your MAC address was blocked, you have no internet connection . . . How are you currently "Online"?